The present invention concerns a feed arrangement for a typing ribbon and/or a correction ribbon for typing machines comprising an electromagnetic arrangement having an excitation winding and an output member capable of alternating movement, a drive element for the feed movement of the ribbon, and a connecting mechanism interposed between the output member and the drive element for converting the alternating movement of the output member into a unidirectional movement of the drive element for producing a unidirectional feed movement of the ribbon.
U.S. Pat. No. 4,462,702 assigned to Ing. C. Olivetti & C., S.p.A. discloses a feed arrangement of that type having an electromagnet of rotary type, in which the output member comprises a rotor which is capable of performing a limited rotary movement. The rotor produces the energy for the feed movement of the ribbon, in response to a unidirectional current pulse on the excitation winding of a magnetic stator circuit, and it is returned to the rest condition by a corresponding return spring. As a connecting mechanism, that arrangement has a device with a double tooth configuration and with two toothed wheels, which is interposed between the rotor and a drive element for producing the feed movement of the ribbon, to convert the alternating movement of the rotor into a unidirectional movement of the drive element to feed the ribbon. That feed arrangement is reliable and functional for mounting on a typewriter of standard type, but it is excessively expensive and bulky for fitting to portable typewriters in the medium-low range in which both cost and size are to be kept down as far as possible.